Farming and Pests Flashcards
What methods of intensive farming do you know? (10)
• Selective breeding. Most of the increases in primary productivity are due to selective breeding of crops and farm animals that grow faster and bigger
• Fertilisers. Primary productivity is often limited by the availability of minerals in the soil, so fertilisers overcome this limitation and increase productivity.
• Pest Control. Loss of crops to pests decreases net productivity, so pest control measures increase productivity.
• Factory Farming*. By rearing livestock indoors and feeding them specialised diets energy losses due to heat, movement and egestion are reduced. This increases net secondary productivity.
• Large Fields mean less farmland is wasted with hedgerows and field margins, so overall productivity for the land is increased.
• Monoculture means farmers can specialise in one type of crop and find the optimum conditions for maximum productivity.
• Mechanisation means crops can be sown and harvested more quickly and reliably, cows can be milked
more quickly and money can be saved by employing fewer farm workers.
What is intensive farming?
Farming designed to maximise yield of produce (crop/meat/milk etc.) by making use of any appropriate technology such as agrochemicals, machinery, etc. Most farms in the UK are intensively farmed.
What is monoculture?
Growing a single crop in a field.
What is a pest?
Any organism that harms crops. Can include animals, other plants or microbes.
What is a weed?
Any plant growing in a farm that the farmer doesn’t want.
What is eutrophication?
Eutrophication refers to the effects of nutrients on aquatic ecosystems. In particular it means a sudden and dramatic increase in nutrients due to human activity, which disturbs and eventually destroys the food web. The main causes are fertilisers leaching off farm fields into the surrounding water course, and sewage (liquid waste from houses and factories). These both contain dissolved minerals, such as nitrates and phosphates, which enrich the water.
What is biological control?
As an alternative to chemical pest control, pests can be controlled using other living organisms to keep the pest numbers down – biological pest control. The organisms can be predators, parasites or pathogens, and
the aim is to reduce the pest population to a level where they don’t do much harm – the economic threshold. A new equilibrium should be reached where the pest and predator numbers are both kept low.
Tell me about insecticides…
Insects are the most important group of animal pests, like aphids and leatherjackets that eat the crop and so reduce yield. Insecticides can be contact or systemic. Contact insecticides remain on the surface of the crop and only kill insects that come into contact with it, so are not 100% effective.
Systemic insecticides are absorbed into the crop and transported throughout the plant, so any insect feeding on the crop will be killed.
What does biodegradable mean?
Biodegradable, which means they are broken down by decomposers in the soil. Early pesticides were
not easily broken down (they were persistent), so they accumulated in food chains and harmed humans
and other animals, but modern pesticides biodegradable so they do not leave residues on crops.
What is DDT?
One of the most famous insecticides is DDT, which was used very successfully from the 1940s to 80s and was responsible for eradicating malaria from southern Europe.
However DDT was non-selective and persistent, so it accumulated in the food chain and killed sea birds and other top predators. DDT was banned in developed countries in 1970, and the bird populations
have since recovered.
What are the advantages of biololgical control?
introduction of a predator
Cheap as only one application needed (originals go on to breed)
Pests do not usually develop resistance
Usually more specific compared with chemical pesticides
No bioaccumulation
What does a herbicide kill?
weeds
What does an insecticide kill?
Insects
Why might using a biological control be unhelpful?
It might affect populations other than the pest
It might not be able to reproduce in the new environment
Reducing the pest numbers might allow another pest to occupy the original niche
What is integrated control ?
Where both chemical and biological control are used
